cpu-hotplug: replace per-subsystem mutexes with get_online_cpus()
This patch converts the known per-subsystem mutexes to get_online_cpus
put_online_cpus. It also eliminates the CPU_LOCK_ACQUIRE and
CPU_LOCK_RELEASE hotplug notification events.
Signed-off-by: Gautham R Shenoy <ego@in.ibm.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
diff --git a/kernel/sched.c b/kernel/sched.c
index 672aa68..c0e2db6 100644
--- a/kernel/sched.c
+++ b/kernel/sched.c
@@ -439,7 +439,6 @@
};
static DEFINE_PER_CPU_SHARED_ALIGNED(struct rq, runqueues);
-static DEFINE_MUTEX(sched_hotcpu_mutex);
static inline void check_preempt_curr(struct rq *rq, struct task_struct *p)
{
@@ -4546,13 +4545,13 @@
struct task_struct *p;
int retval;
- mutex_lock(&sched_hotcpu_mutex);
+ get_online_cpus();
read_lock(&tasklist_lock);
p = find_process_by_pid(pid);
if (!p) {
read_unlock(&tasklist_lock);
- mutex_unlock(&sched_hotcpu_mutex);
+ put_online_cpus();
return -ESRCH;
}
@@ -4592,7 +4591,7 @@
}
out_unlock:
put_task_struct(p);
- mutex_unlock(&sched_hotcpu_mutex);
+ put_online_cpus();
return retval;
}
@@ -4649,7 +4648,7 @@
struct task_struct *p;
int retval;
- mutex_lock(&sched_hotcpu_mutex);
+ get_online_cpus();
read_lock(&tasklist_lock);
retval = -ESRCH;
@@ -4665,7 +4664,7 @@
out_unlock:
read_unlock(&tasklist_lock);
- mutex_unlock(&sched_hotcpu_mutex);
+ put_online_cpus();
return retval;
}
@@ -5625,9 +5624,6 @@
struct rq *rq;
switch (action) {
- case CPU_LOCK_ACQUIRE:
- mutex_lock(&sched_hotcpu_mutex);
- break;
case CPU_UP_PREPARE:
case CPU_UP_PREPARE_FROZEN:
@@ -5697,9 +5693,6 @@
spin_unlock_irq(&rq->lock);
break;
#endif
- case CPU_LOCK_RELEASE:
- mutex_unlock(&sched_hotcpu_mutex);
- break;
}
return NOTIFY_OK;
}
@@ -6655,10 +6648,10 @@
{
int err;
- mutex_lock(&sched_hotcpu_mutex);
+ get_online_cpus();
detach_destroy_domains(&cpu_online_map);
err = arch_init_sched_domains(&cpu_online_map);
- mutex_unlock(&sched_hotcpu_mutex);
+ put_online_cpus();
return err;
}
@@ -6769,12 +6762,12 @@
{
cpumask_t non_isolated_cpus;
- mutex_lock(&sched_hotcpu_mutex);
+ get_online_cpus();
arch_init_sched_domains(&cpu_online_map);
cpus_andnot(non_isolated_cpus, cpu_possible_map, cpu_isolated_map);
if (cpus_empty(non_isolated_cpus))
cpu_set(smp_processor_id(), non_isolated_cpus);
- mutex_unlock(&sched_hotcpu_mutex);
+ put_online_cpus();
/* XXX: Theoretical race here - CPU may be hotplugged now */
hotcpu_notifier(update_sched_domains, 0);
